1. Field of the Invention
There is currently a burgeoning of interest in reciprocating floors as a vehicle for the loading and unloading of both stationary storage facilities and mobile facilities such as tractor/trailers. Such trailers were typically open at the top and loading was very easy.
Whereas it was common in most locales about the country to load storage and transportable facilities, for particulate materials in particular, by use of a skip loader, or perhaps a conveyer, and even by blowing the material into the space, unloading of such facilities with that kind of equipment proved to be less convenient.
Moreover, with the advent of the passage of laws in many states requiring the covering of such loads, the time required to tarp and untarp a load of, for example, grain, must be figured into the total cost of shipment and storage.
As a consequence, covered vans or trailers actually provided a saving in labor and, coincidently, permitted the load to be enclosed, thereby minimizing losses of material. With the advent and development of reciprocating floors, labor and related costs were capable of being minimized, and the use of such systems has enjoyed great acceptance among shippers and growers alike.
The essence of such systems is the reciprocation of a series of contiguous parallel beams in a controlled sequence, and while there are a variety of more or less mechanical and even electrical systems, the use of fluid motors is perhaps the most efficient and trouble free.
While hydraulic systems are generally considered to be relatively less susceptible to damage from shock, reciprocating floors routinely experience damage to various moving parts, perhaps because of the transverse loading on the floor beams. It has been specifically determined that, as a consequence of the number of hydraulic pistons that are employed in reciprocating floor systems, all of which have to be continuouosly sequenced, that the system experiences a series of pressure surges, or spikes, which raise local system pressures to a multiple of pump output pressure, resulting in blow outs in the system. The consequential damage can result in a spectrum of malfunctions ranging from the premature opening of standard sequencing valves to literally shutting down the entire system. Repairs are both time consuming and expensive to the operator.
To a somewhat lesser extent, but no less debilitating, are accelerated wear problems and sealing problems. By virtue of the nature of the products handled by reciprocating floor systems, and the sensitivity of fluid systems to gritty materials and particulate generally, existing systems typically experience relatively frequent maintenance cycles and seal wear, which results in exaggerated loss of loads. Finally, valving in particular seems vulnerable to the higher level of macroscopic particulate which is inevitably present and airborne as the floor is operating.
2. Overview of the Prior Art
There appears to be a dearth of patent art directed at the driving or motivation of reciprocating floor systems. Most manufacturers have adopted existing technology to very simple systems which sometimes incorporate mechanical or electrical switching systems, with manufacturers and operators alike seemingly willing to give docile, yet grudging acceptance, to a maintenance and repair regime of relatively high frequency, with its attendant relatively high costs.
Referring to the Quaeck U.S. Pat. No. 5,222,593, a system for the hydraulic reciprocation of a reciprocating floor is disclosed, and it perhaps reflects the current wisdom in the industry. Quaeck makes it clear that systems such as that set forth in this specification have achieved recognition in the art as a specialized art.
In Quaeck there is a basic fluid motor acutated plan of operation for what Quaeck refers to as slats. In order, however, to sequence the motors to effect the appropriate operation of the reciprocating floor, each fluid motor is equipped with a fluid-driven timing cylinder, designated respectivly, CT1, CT2 and CT3, which are controlled by soleniod valves, (SV+a number), each having a number representing the cylinder being controlled. Separate limit switches (S+a number) are also provided to detect arrival of the slats at a predetermined position. All of these elements of the system are subject to wear and maintenance, and none provide the shock absorbsion, the absense of which tends to plague such systems due to the shock loading on the drive cylinder.
The use of valves, e.g., spool valves, is common in many hydraulic systems, and as seen in Taylor U.S. Pat. No. 5,297,575, a piston may be used in some applications as a rudimentary open/close switching element. Taylor, of course, relates to a pressure relief valve and has no application to the present invention. The present system, however, accomplishes the objectives attributed to it without resort to these techniques, as will be evident from a reading of the detailed description.